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<title>GnuTLS 3.5.4: Echo server with SRP authentication</title>
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<a name="Echo-server-with-SRP-authentication"></a>
<div class="header">
<p>
Next: <a href="Echo-server-with-anonymous-authentication.html#Echo-server-with-anonymous-authentication" accesskey="n" rel="next">Echo server with anonymous authentication</a>, Previous: <a href="Echo-server-with-X_002e509-authentication.html#Echo-server-with-X_002e509-authentication" accesskey="p" rel="prev">Echo server with X.509 authentication</a>, Up: <a href="Server-examples.html#Server-examples" accesskey="u" rel="up">Server examples</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Function-and-Data-Index.html#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<a name="Echo-server-with-SRP-authentication-1"></a>
<h4 class="subsection">7.2.2 Echo server with <acronym>SRP</acronym> authentication</h4>
<p>This is a server which supports <acronym>SRP</acronym> authentication. It is
also possible to combine this functionality with a certificate
server. Here it is separate for simplicity.
</p>
<pre class="verbatim">/* This example code is placed in the public domain. */
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <string.h>
#include <unistd.h>
#include <gnutls/gnutls.h>
#define SRP_PASSWD "tpasswd"
#define SRP_PASSWD_CONF "tpasswd.conf"
#define KEYFILE "key.pem"
#define CERTFILE "cert.pem"
#define CAFILE "/etc/ssl/certs/ca-certificates.crt"
/* This is a sample TLS-SRP echo server.
*/
#define SOCKET_ERR(err,s) if(err==-1) {perror(s);return(1);}
#define MAX_BUF 1024
#define PORT 5556 /* listen to 5556 port */
int main(void)
{
int err, listen_sd;
int sd, ret;
struct sockaddr_in sa_serv;
struct sockaddr_in sa_cli;
socklen_t client_len;
char topbuf[512];
gnutls_session_t session;
gnutls_srp_server_credentials_t srp_cred;
gnutls_certificate_credentials_t cert_cred;
char buffer[MAX_BUF + 1];
int optval = 1;
char name[256];
strcpy(name, "Echo Server");
if (gnutls_check_version("3.1.4") == NULL) {
fprintf(stderr, "GnuTLS 3.1.4 or later is required for this example\n");
exit(1);
}
/* for backwards compatibility with gnutls < 3.3.0 */
gnutls_global_init();
/* SRP_PASSWD a password file (created with the included srptool utility)
*/
gnutls_srp_allocate_server_credentials(&srp_cred);
gnutls_srp_set_server_credentials_file(srp_cred, SRP_PASSWD,
SRP_PASSWD_CONF);
gnutls_certificate_allocate_credentials(&cert_cred);
gnutls_certificate_set_x509_trust_file(cert_cred, CAFILE,
GNUTLS_X509_FMT_PEM);
gnutls_certificate_set_x509_key_file(cert_cred, CERTFILE, KEYFILE,
GNUTLS_X509_FMT_PEM);
/* TCP socket operations
*/
listen_sd = socket(AF_INET, SOCK_STREAM, 0);
SOCKET_ERR(listen_sd, "socket");
memset(&sa_serv, '\0', sizeof(sa_serv));
sa_serv.sin_family = AF_INET;
sa_serv.sin_addr.s_addr = INADDR_ANY;
sa_serv.sin_port = htons(PORT); /* Server Port number */
setsockopt(listen_sd, SOL_SOCKET, SO_REUSEADDR, (void *) &optval,
sizeof(int));
err =
bind(listen_sd, (struct sockaddr *) &sa_serv, sizeof(sa_serv));
SOCKET_ERR(err, "bind");
err = listen(listen_sd, 1024);
SOCKET_ERR(err, "listen");
printf("%s ready. Listening to port '%d'.\n\n", name, PORT);
client_len = sizeof(sa_cli);
for (;;) {
gnutls_init(&session, GNUTLS_SERVER);
gnutls_priority_set_direct(session,
"NORMAL"
":-KX-ALL:+SRP:+SRP-DSS:+SRP-RSA",
NULL);
gnutls_credentials_set(session, GNUTLS_CRD_SRP, srp_cred);
/* for the certificate authenticated ciphersuites.
*/
gnutls_credentials_set(session, GNUTLS_CRD_CERTIFICATE,
cert_cred);
/* We don't request any certificate from the client.
* If we did we would need to verify it. One way of
* doing that is shown in the "Verifying a certificate"
* example.
*/
gnutls_certificate_server_set_request(session,
GNUTLS_CERT_IGNORE);
sd = accept(listen_sd, (struct sockaddr *) &sa_cli,
&client_len);
printf("- connection from %s, port %d\n",
inet_ntop(AF_INET, &sa_cli.sin_addr, topbuf,
sizeof(topbuf)), ntohs(sa_cli.sin_port));
gnutls_transport_set_int(session, sd);
do {
ret = gnutls_handshake(session);
}
while (ret < 0 && gnutls_error_is_fatal(ret) == 0);
if (ret < 0) {
close(sd);
gnutls_deinit(session);
fprintf(stderr,
"*** Handshake has failed (%s)\n\n",
gnutls_strerror(ret));
continue;
}
printf("- Handshake was completed\n");
printf("- User %s was connected\n",
gnutls_srp_server_get_username(session));
/* print_info(session); */
for (;;) {
ret = gnutls_record_recv(session, buffer, MAX_BUF);
if (ret == 0) {
printf
("\n- Peer has closed the GnuTLS connection\n");
break;
} else if (ret < 0
&& gnutls_error_is_fatal(ret) == 0) {
fprintf(stderr, "*** Warning: %s\n",
gnutls_strerror(ret));
} else if (ret < 0) {
fprintf(stderr, "\n*** Received corrupted "
"data(%d). Closing the connection.\n\n",
ret);
break;
} else if (ret > 0) {
/* echo data back to the client
*/
gnutls_record_send(session, buffer, ret);
}
}
printf("\n");
/* do not wait for the peer to close the connection. */
gnutls_bye(session, GNUTLS_SHUT_WR);
close(sd);
gnutls_deinit(session);
}
close(listen_sd);
gnutls_srp_free_server_credentials(srp_cred);
gnutls_certificate_free_credentials(cert_cred);
gnutls_global_deinit();
return 0;
}
</pre>
<hr>
<div class="header">
<p>
Next: <a href="Echo-server-with-anonymous-authentication.html#Echo-server-with-anonymous-authentication" accesskey="n" rel="next">Echo server with anonymous authentication</a>, Previous: <a href="Echo-server-with-X_002e509-authentication.html#Echo-server-with-X_002e509-authentication" accesskey="p" rel="prev">Echo server with X.509 authentication</a>, Up: <a href="Server-examples.html#Server-examples" accesskey="u" rel="up">Server examples</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Function-and-Data-Index.html#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
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